A hydrostatic-mechanical tractor transmission with a continuously variable hydrostatic drive train is known from DE 10 2006 025 348 A1. The hydrostatic drive train has a hydrostatic pump driven by an internal combustion engine and a hydraulic motor driven by the pump. The pump and the hydraulic motor are forcibly coupled via a single, common pivoting part and can be adjusted such that the pump is pivoted between a minimum angle and a maximum angle, while the motor synchronously pivots from a maximum pivot angle to a minimum angle at the same time. The pump is designed for only one conveying direction. A mechanical range transmission with several shift steps, which can be shifted via a clutch, is provided downstream.
Furthermore, a transmission device comprising a power split unit is known from DE 19 52 966 A which has a variator, a double planetary gear set and a manual transmission device to implement the drive ranges. The pump and motor means of the variator configured as a hydrostatic device can be adjusted via a common yoke.